Interpretive Summary: Infection by the protozoan parasite, Toxoplasma gondii is widely prevalent in man animals. Humans become infected with T. gondii by ingesting stages of the parasite encysted (tissue cysts) in edible tissues of infected animals and by ingesting food and water contaminated with oocysts (a resistant stage of the parasite) from feces of infected cats. Infection in birds and small mammals is of epidemiologic significance because cats are thought to become infected with T. gondii by preying on them; cats are the only hosts that can excrete oocysts of T. gondii. Infections in birds are usually asymptomatic. Scientists at the Beltsville Agricultural Research Center and the Montreal University in Quebec, Canada report the first fatal case of toxoplasmosis in a raptor, Barred Owl. These findings will be of interest to veterinarians and wildlife biologists.

Technical Abstract:
Toxoplasmosis was diagnosed in a female adult barred owl (Strix varia). The bird had been hurt by a car and was affected by an hyphema. Its general status declined gradually within 2 wks with anorexia and inactivity. Necropsy examination revealed marked multifocal pale areas in liver, emaciation and minimal air sacculitis and pericarditis. Histopathologic examination revealed marked multifocal acute hepatic necrosis with numerous protozoal tachyzoites within necrotic foci, in the cytoplasm of hepatocytes and macrophages. These tachyzoites stained with an indirect immunohistochemistry method for Toxoplasma gondii antigens. This is the first reported case of clinical toxoplasmosis in a raptor.